They were greeted at the airport by Kansas University ecology professor Chip Taylor, who also heads Monarch Watch.

"Nothing like this has been done," Taylor said. "It's really a marvelous adventure and one that very few people would even think about as a possibility because it is risky."

Although the general migration route is known, the possible obstacles facing someone on an ultralight are not, Taylor said. The weather also could be a factor.

Gutierrez, who said he had flown an ultralight over mountains in Mexico, shrugged off the difficulties weather might cause.

"If the monarchs don't fly, I don't fly," he said.

But Gutierrez has also seen hundreds of them at a time, such as near Ontario, Canada, as the monarchs were ready to cross Lake Erie.

Gutierrez, who is from Mexico, took off in his ultralight Aug. 21 in Montreal and is following one of the migration routes, which cuts a swath through the Midwest and passes through Kansas. Several monarchs could be seen flying near the ground near the airport.

The ultralight's 32-foot wingspan has a monarch painted on top of it and he has given his aircraft the name, Papalotzin. The word means "royal butterfly" in the Nowati language once spoken by the Aztecs but which is still spoken by many today in Mexico, said Tania Guerrero Collazo, a member of the ground crew who also is from Mexico.

The Papalotzin crew saw many monarchs when they passed through the Shenandoah National Park in Tennessee and then near St. Louis.

The crew will be in Lawrence until Tuesday and is filming interviews and monarch tagging exercises with Taylor. They hope the documentary and publicity about it brings public awareness of the Monarch and related conservation issues.

He was excited to hear about the monarchs spotted by Gutierrez at 3,500 feet.

"This is perfect," Taylor said. "That is exactly what I anticipated they would find today."

A documentary film crew surrounds Francisco "Vico" Gutierrez and Tania Guerrero Collazo at Lawrence Municipal Airport Sunday afternoon. The fliers stopped in Lawrence for a stay during their journey following the migration of the Monarch butterfly.

Monarchs catch warm air currents or swirls known as thermals, which lift the butterflies high into the air. They then set themselves for a glide to the southwest when they hit a laminar air flow.

"Monarchs do this quite a bit but we don't how much they do it," Taylor said.

Monarchs are the largest insect to fly at such a high elevation. They are generally left alone by birds, apparently because the birds don't find them tasty enough, Taylor said.

The Papalotzin crew will travel on into Texas and cross into Mexico as the monarchs make their way to sanctuaries in central Mexico. Taylor will be with the crew at 2 p.m. today at the Baker Wetlands for a short period of monarch tagging. He said anyone was welcome to come and watch.

This year's monarch population is strong and the migration through the Lawrence area should continue until about Oct. 4, Taylor said.

Also at the airport Sunday was Kay Milam, of Louisville, Ky., who is with an independent film crew also making a documentary about migrating monarchs and the people interested in them.

"It follows the migration but it is as much about the people who are passionate about monarchs," she said. "The story is told through their eyes."